This invention relates generally to the separation of thin partially etched parts from a strip of base material and particularly to the separation of shadow masks for color television tubes from a strip of material.
In the most common technique presently employed in the manufacture of shadow masks for color television tubes a light gage steel strip is coated with a photoresist material. An aperture pattern and the periphery of the shadow mask are photographically applied to the photoresist which then is exposed to ultraviolet light and developed. The aperture pattern is completely etched through and the periphery of the shadow mask is completely etched through in some areas and partially etched through in other areas. The remainder of the photoresist material is then removed from the base material and the shadow mask remains attached to the strip of base material. The separation of the shadow mask from the strip of base material typically is accomplished by a manual operation in which the partially etched areas of the shadow mask periphery, known as the strip out line, are broken away.
This technique of removing shadow masks is satisfactory but suffers the disadvantage of being a manual operation. As a consequence, an unduely high percentage of the shadow masks are damaged and the manufacturing process is slowed because automatic separation is not used.
The instant invention overcomes these difficulties by providing the automatic separation of shadow masks from the strip of base material.